1. Field of the Invention
The present invention relates to an image forming apparatus and, more particularly, to the replacement of a sheet feeding (supplying) unit in the case where a plurality of sheet storage units is provided in a main body of an image forming apparatus.
2. Description of Related Art
In some of conventional image forming apparatuses such as a copying machine and a printer, a plurality of sheet storage units is superposed at the lower section of a main body of an image forming apparatus or is arranged in a lateral direction, so that the number of sheets that can be fed is increased, and further, sheets having different sizes can be used.
A sheet feeding cassette serving as a sheet storage unit is provided with a sheet supporting plate serving as a sheet stacking member that can be moved in a vertical direction in which a sheet is stacked. Moreover, on the side of the main body of the image forming apparatus are provided a lifting and lowering mechanism for lifting and lowering the sheet supporting plate and a feeding roller constituting a sheet feeding unit for feeding the sheet stacked on the sheet feeding cassette.
When the sheet feeding cassette is installed in the main body of the image forming apparatus, the lifting and lowering mechanism lifts the sheet supporting plate, and thus, the sheet stacked on the sheet supporting plate is moved to a position at which the sheet can be supplied/fed by the feeding roller. Thereafter, when one out of the plurality of sheet feeding cassettes is selected, the sheet stacked on the selected sheet feeding cassette is supplied/fed by the feeding roller located above the selected sheet feeding cassette.
In the meantime, if the feeding roller is degraded due to abrasion or the like in the conventional image forming apparatus, sheet feeding performance is deteriorated. Therefore, the feeding roller need be replaced with a new one periodically or in much abrasion amount. At this time, in order to facilitate the replacement of the feeding roller, the feeding roller has been detachably attached to the main body of the image forming apparatus in the related art (see Japanese Patent Laid-Open No. 2004-256287). Alternatively, the feeding roller has been replaced by using a roller replacing tool (see Japanese Patent Laid-Open No. 2000-264485).
Here, in the case where the feeding roller is configured in a detachably attachable manner, the sheet feeding cassette need be detached, and then, the feeding roller need be replaced, since the feeding roller is disposed above the sheet feeding cassette. However, in the case where the feeding roller is located at the lower section of the main body of the image forming apparatus, the feeding roller cannot be visually recognized even if the sheet feeding cassette is detached. In this case, a replacement section is peeped through a clearance produced by detaching the sheet feeding cassette, and further, a hand need be inserted through the clearance, followed by replacement of the feeding roller.
On the other hand, in the case where the feeding roller is located at the lower section of the main body of the image forming apparatus, a worker need work with his/her eyes under his/her waist, resulting in poor workability. Moreover, there is a possibility that the sheet feeding cassette may not be detached in the case where the sheet feeding cassette has a large capacity. In this case, a worker need work in the state in which the sheet feeding cassette is kept drawn, so that it becomes more difficult to replace the feeding roller because of the hindrance of the large-capacity cassette to the standing position of a worker.
The present invention has been accomplished in view of the above-described current circumstances. Therefore, it is desirable to provide an image forming apparatus, in which a sheet feeding unit can be readily replaced.